The Pear Psylla. 109 



"branches and trunk. They are not easily seen as they are so small 

 and their color so closely imitates the bark. 



Egg-laying of the winter hrood. — During the iirst warm spring 

 weather the adults come from their hiding places, copulate, and 

 egg-laying soon begins. In this State, most of the eggs are usually 

 laid before April 25. They are placed in the creases of the bark 

 or in old leaf scars, about the bases of the terminal buds of the 

 preceding year's growth ; some occur about the side buds, near the 

 terminal ones. They are usually laid singly, but 

 rows of eight or ten sometimes occur. The eggs 

 (Fig. 42) are scarcely visible to the unaided eye : 



. . . 42.— Ekp of pear psylla, 



it would take eighty of them placed end to end greatly enlarged, 

 to measure an inch. They are elongate pyriform in shape, smooth 

 and shining, and of a light orange-yellow color when first laid, 

 becoming darker before hatching. A short stalk on the larger end 

 attaches the eg^ to the bark, and a long thread-like process pro- 

 jects from the smaller end. 



The temperature conditions in the spring influence the time of 

 oviposition and the duration of the egg- state. In 1892, the eggs 

 were from seventeen days to three weeks in hatching. Hatching 

 usually begins about May 10. By the 18th most of the nymphs 

 are out and their parents have disappeared. 



Habits of the nymphs. — Immediately after emerging, which 

 usually happens about the time the leaves are expanding, the 



minute nymph (Fig. 43) seeks its favorite feed- 

 ing place, the axils of the leaf petioles, and 

 later on stems of the forming fruit. "When 

 these axils become full they gather on the 

 leaves. Their food consists entirely of the sap 

 of the tree, which they suck through a short, 

 ^^irympiro/pea^r*fsyita^, sharp bcak. Unlcss disturbed, they move about 



ventral view, greally i , Ti.i.1 j.- i • • i 



enlarged. (Reduced but vcry little, sometimes becoming covered 

 Dept. ofAgr). ' ' with their own honey-dew. They stop feeding 



only when their skin gets too small, and they cast it off for a new 



elastic one that they grow just beneath the old one. 



Habits of the adult. — The strong legs and wings of the adult 



enable it to spring up and fly away with surprising quickness upon 



the slightest unnatural jar. The hibernating forms are not as 



